This invention relates to an electromagnet for use with an electrically controlled brake. While the electromagnet of the invention may be used with various types of brakes, it is particularly suitable for use in conjunction with a brake for a vehicle wheel. In such a brake, the electromagnet is mounted on a pin which is carried on the free end of a pivoted operating arm. When energized, the electromagnet frictionally engages an armature plate which rotates with and usually forms part of the drum of the vehicle wheel structure. Such frictional engagement causes the operating arm to pivot and force one or more brake shoes into engagement with the drum to apply braking torque to the wheel. In certain instances, two electromagnets are mounted in side-by-side relation on the free end of the operating arm.
Many electromagnets which are used with wheel brakes are circular in shape. Such an electromagnet usually comprises a shell made of magnetic metal and having radially spaced concentric poles of opposite polarity, the annular space between the poles being filled with a ring of non-magnetic friction material. An electric coil is located within the shell and, when the coil is excited, magnetic flux pulls the poles into frictional engagement with the armature plate. The friction ring also engages the armature and serves as the principal friction face of the electromagnet.